New insights into hand, foot, and mouth disease epidemics in China

Rachel Tompa

Incidence of hand, foot, and mouth disease in China by week in 2008 and 2009.

Hand, foot, and mouth disease affects mainly children 5 years old and under, is caused by different types of enterovirus and in most forms normally not severe. However, one type of hand, foot, and mouth disease, caused by the virus EV71, can have dramatic effects, including nerve damage, paralysis or death. EV71 also appears to be very pathogenic, and in recent years has caused large and worrying outbreaks in children in Asian countries, especially in China. Infection rates in that country have continued to mount each year since 2007. Through a new collaboration with the Chinese Center for Disease Control and Prevention, VIDD scientists have helped analyze the epidemiology of this pandemic hand, foot, and mouth disease in China.

The CCDC has collected copious amounts of data on outbreaks of hand, foot, and mouth disease starting in mid-2008 using their extensive surveillance system that amasses data nation-wide from more than 300,000 clinics. Led by VIDD assistant member Dr. Yang Yang, CCDC, University of Washington and VIDD scientists, including VIDD co-director Dr. Steve Self, affiliate investigator Dr. Ira Longini, and senior project manager Dr. Lena Yao, analyzed these data to look for spatial-temporal patterns of and potential risk factors for the spread of the disease across China in 2008 and 2009. They found that children aged 1-3 years old were the most susceptible to hand, foot, and mouth disease, but infants had the highest rates of severe complications from the disease; most severe complications are due to infection with EV71 rather than other enteroviruses. The disease peaked in the spring in most areas of China, and subsided in the summer. There was another peak in the fall, coinciding with the start of the school year. The exact reasons for these outbreaks remain unclear. The researchers found that higher temperatures, humidity, and wind speeds also affect disease transmission. These data and epidemiological analyses of hand, foot, and mouth disease lay the groundwork for modeling the spread of this disease and for evaluating the effects of possible interventions at the population level.